It has been conventionally known that a certain phthalamide derivative is useful as an agricultural or horticultural insecticide (For example, refer to Patent Document 1). Furthermore, it is known that a phthalamide derivative having a similar structure to that of the present invention is useful as an agricultural or horticultural insecticide (For example, refer to Patent Document 2). However, the compound of the present invention having a tetrazolyl group in the structure thereof has been neither described nor suggested.    Patent Document 1: JP-A-11-240857    Patent Document 2: JP-A-2001-131141